The flamethrowers we will need will probably have to be handheld for defense against very small but very dangerous enemies and later we will need ones for the mechs we scrounge up. (by the end the only people who won't have mechs are the people who don't want one)
At first we won't have spider-mechs we will have one or two of
these or
these because they are cheap (the second is way cheaper than the first because it's a civilian model that was modified for military use and I know they were taken straight out of Lost Planet but they were the kind of mechs I was looking for to be cheap and easy to build and maintain) and the project to send so many people to such a distant planet put a huge drain on the entire world's economy and they can't afford to send the team with anything more expensive. We will also have a mobile command unit (MCU) that has been modified to, instead of carry passengers, carry water, food and extra fuel as well as any spare parts, ammo or weapons we might find or build. I'm still looking for a picture for the MCU but I know that it will be about the size of a paneled van and have tank treads so that it can move easily through sand.
When it comes to spider-mechs they will usually be heavier (which is why they have 4 legs, because they're too heavy to be supported by 2) but lighter ones could be found as high-mobility units with jumping capabilities.
Your character can have any odd things about them you want, as long as it isn't something that would prevent them from military service. As an engineer you can build anything you can find parts for, which won't be hard in the beginning but as the story goes on mechanical parts and things will be harder to find so stock up on parts you may need early on.
EDIT: Okay, found a few potential MCUs. Tell me what you guys think.